Positive crankcase ventilation (PCV) systems have been used within internal combustion engines to reduce emission of contaminants by recirculating blow-by gases and crankcase vapors, or PCV gases, into combustion chambers of the internal combustion engine for subsequent burning therein. This is commonly accomplished by conducting the PCV gases from a crankcase defined by the internal combustion engine into an intake system or intake manifold where it is subsequently drawn into the combustion chambers. If the gases are drawn into an intake manifold, a PCV valve is generally required to control the amount of gas flow because the manifold vacuum varies greatly and generally inversely to the amount of PCV gases required to be recirculated. However, where the PCV gases are recirculated into the air intake system, it has been generally satisfactory to control the gas flow by means of an orifice.
The gases which enter the PCV system from the crankcase and flow to the combustion chambers can have oil particles suspended therein. The oil particles can travel through the PCV system, with the PCV gases, to the intake system and combustion chambers in which they are burned with the air and fuel. If the amount of such oil particles becomes excessive, the engine emissions and oil consumption can increase. Therefore, PCV systems can include a filter device for separating oil particles from the gases to reduce the amount of oil which flows to, and is burned within, the combustion chambers. Such a filter device can include a semi-permeable filter element through which the PCV gases flow. The filter element typically has small openings or interstices through which the PCV gases, and the oil particles contained therein, must pass. The openings are sufficiently sized so that the oil is strained from the PCV gases and remains in the filter element. The filter element can become clogged with oil and thereby obstruct the gas flow therethrough. An additional consideration is freezing or icing of the PCV system in cold climates. Condensed water in the PCV system can gather and freeze, obstructing the gas flow or allowing icing of intake system components. Mounting the PCV system components internally to the engine will reduce the risk of icing.